: Includes cooling fan, air hood, etc. Some knapsack spray dusters open a cooling port on the volute of the large fan, and the cooling airflow is led out by the air hood, eliminating the need for a separate cooling impeller.

(5) Lubrication system

: The two-stroke gasoline engine uses a combination of gasoline and lubricating oil to lubricate with the oil supply system. The four-stroke gasoline engine is lubricated separately from the oil supply, and the crankcase is equipped with a lubricating oil gauge.

(6) Gas distribution system

: The four-stroke gasoline engine consists of intake and exhaust valves, rocker arms, push rods, tappets and camshafts. The two-stroke gasoline engine has no intake and exhaust valves, but has an air inlet, an air outlet and a gas exchange port on the cylinder block, and the piston is moved up and down to open or close the air holes.

(7) Starting system

There are two kinds of structures, one is composed of a starting rope and a simple starting wheel; the other is a rebounding starting structure with spring-bonded teeth and a protective cover.

(8) Ignition system

: Includes magneto, high voltage wire, spark plug, etc. There are two types of magneto: a contact type with a jumper structure and a non-contact electronic ignition line.